Fuel metering device for internal combustion engines

ABSTRACT

A fuel metering device for an internal combustion engine wherein the fuel feed pressure of the device is determined by the static height of the fuel in a vessel from which a fuel line leads to a suction tube, is improved by providing therein at least two vessels of different filling level, means for feeding fuel into each of the vessels, valve means for connecting the vessels alternatingly or simultaneously with the fuel line, and control means for actuating the valve means in dependence on characteristic data of the engine.

United States Patent [191 lEckert 1 FUEL METERING DEVHCE FUR INTERNALCOMBUSTION ENGINES [75] Inventor: Konrad Eclrert, Stuttgart, Germany[73] Assignee: Robert Bosch Gmbi-l, Stuttgart,

Germany [22] Filed: June 1, 1973 [21] Appl. No.: 366,099

[30] Foreign Application Priority Data July 18, 1972 Germany 2235146[52] US. Cl 261/36 A, 261/40, 261/67, 26l/DIG.'74

[51] Int. Cl. 802m 7/16 [58] Field of Search 261/36 A, 67, 40, DIG. 74,261/41 B, 41 R, 41 A, 68, 66, 69 R [56] References Cited UNITED STATESPATENTS 1,333,149 3/1920 Anderson 261/36 A 1,616,726 2/1927 Wilcox261/41 B Bronander 261/34 A Mallory 261/36 A 2,759,717 8/1956 Nallinger261/41 R 3,066,922 12/1962 Wucherer 261/41 R 3,171,467 3/1965Featherston 261/36 A 3,252,498 5/1966 Ball 261/36 A 3,275,307 9/1966Robechaud 261/36 A 3,685,502 8/1972 Oberdorfer, Jr. 261/69 R FOREIGNPATENTS OR APPLICATIONS 383,256 2/1931 Great Britain 261/41 R 1,337,2848/1963 France 261/67 Primary Examiner-Tim R. Miles Attorney, Agent, orFirm-Edwin E. Greigg 5 7 ABSTRACT A fuel metering device for an internalcombustion engine wherein the fuel feed pressure of the device isdetermined by the static height of the fuel in a vessel from which afuel line leads to a suction tube, is improved by providing therein atleast two vessels of different filling level, means for feeding fuelinto each of the vessels, valve means for connecting the vessels a1ternatingly or simultaneously with the fuel line, and control means foractuating the valve means in dependence 0n characteristic data of theengine.

15 Claims, 5 Drawing Figures PATENTED 1519M 3.841 .613

sum 2 BF 2 Fig. 4

FUEL METERING DEVICE FOR INTERNAL COMBUSTION ENGINES BACKGROUND OF THEINVENTION This invention relates to a fuel metering device for internalcombustion engines in which the fuel feed pressure is determined by aconstant static height of the fuel in a vessel from which a fuel lineleads to a suction pipe.

Under present-day technical requirements. the purpose of such fuelmetering device is to provide in an Otto engine, automatically and underall operational conditions, a favorable fuel/air mixture ratio, in orderto burn the fuel as completely as possible and thereby to avoid ornotably reduce the production of toxic exhaust gases while maintainingan optional, performance of the internal combustion engine at thesmallest possible consumption of fuel. Tothis end it is necessary tometer the fuel in amounts corresponding very accurately to therequirements of every operating condition of the internal combustionengine. This means that a variation in the normal proportions of air andfuel must be attainable, in dependence on such engine data as speed,load and temperature.

OBJECT AND SUMMARY OF THE INVENTION In the case of the known fuelmetering devices of the initially mentioned type (i.e., carburetors),very costly means are usually provided to meet the stated requirements,whereas it is an object of the invention to provide a fuel meteringdevice of the type initially referred to which renders theabove-mentioned data-dependent variation of the fuel/air ratioattainable by very simple means.

This object is achieved according to the invention, in that at least twovessels of different filling height are provided which can be suppliedwith fuel and which are connectable alternatingly or simultaneously witha fuel supply line by means of a valve operated in dependence on thecharacteristic engine data, and wherein this valve operates preferablytogether with electric means, and the controlled switchings take placein a cycle. When the control shifts take place at a high enoughfrequency, any number of intermediary potentials can come into effectbetween the two pressure potentials impressed by the difference infilling height, depending upon which actual magnitude of the fuel/airratio is desired. The actual magnitude is detected by known means, forinstance by an oxygen sampling device in the flow of exhaust gases.Electronic devices can be used in particular for the automatic controlsystem, which can be arranged in a known manner in a centralized controlunit. By shifting to differential pressure levels, a multiplicativecontrol is obtained, independently of carburetor systems coupled at theoutlet side, such as a Stromberg system, and also independently of avariety of possible subsequently arranged injection lines and/or chokes.After shifting, the respective set pressure level is immediatelyeffective without any significant transition periods.

Further objects and advantages of the invention will become apparentfrom the ensuing description of preferred but merely exemplaryembodiments taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 represents schematically asectional view of a first embodiment of the fuel metering deviceaccording to the invention;

FIG. 2 shows a fuel feed pumpand flushing tank arrangem ent differentfrom that employed in the embodiment shown in FIG. 1;

FIG. 3 shows yet another fuel feed pumpand flushing tank arrangement;

FIG. 4 shows a simplified fuel feed pipe arrangement employed in lieu ofthe fuel pumpand flushing arrangement shown in the preceding figures;and

FIG. 5 shows another embodiment of the fuel metering device according tothe invention, all of FIGS. 2 to 5 being highly schematical sectionalviews.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS fuel accumulates in a chamber10 surrounding vessels 2 and 3 and flows via a fuel return line 11 intoa flushing tank 12, whose outlet 13 is controlled by the float l4, andback to reservoir 8 via line 15. In dependence on the static levelexisting between the flushing tank 12 and the fuel reservoir 8, a pump16 can be interposed in the feed line 15, as shown by dotted lines.

Alternatively, fuel line 15 may also be connected by means of a bridgingline 17 (shown by a dashed line) to the branch of fuel line 9 extendingfrom reservoir 8 to the suction side of pump 7.

Owing to this arrangement, the vessels 2 and 3 are always maintainedfull in a simple manner, and any fuel fed into them in excess willoverflow and leave chamber 10 to be reintroduced into the fuel cycle.The vessels 2 and 3 are connected by way of ducts 19 and 20 withchambers 21 and 22 of asolenoid valve 28 which in turn connects thechambers 21 and 22 alternatingly or simultaneouslywith a chamber 23,which latter is linked by way of a line 24 to a nozzle 26 arranged in asuction tube 25. An exciter coil 27 constitutes the electricallyenergizable member of the solenoid valve 28 and is energized by acontrol unit (not shown) which is adapted for processing engine data.Depending on the volume of air flowing through the suction tube 25,which volume is controlled by a throttle valve 29, and

depending on whether chamber 21 or chamber 22 is connected with chamber23, a different amount of fuel will be mixed with this air. In thearrangement shown in FIG. 2, fuel is conveyed from the fuel reservoir 8by means of pump 30 to the flushing tank 12 and from the latter by meansof a pump 31 to the housing 1 (shown in FIG. 1). Excess fuelbeingrecycled from housing 1 is fed into flushing tank 12 via fuel returnline 11 in the same manner as shown in FIG. 1.

In the arrangement shown in FIG. 3, excess fuel is withdrawn fromchamber 10 via fuel return line 11 and conveyed by means of a pump 32 tothe flushing tank 12, from which tank it is recycled due to gravity vialine 9 into the housing 1. Consumed fuel is replaced by means of pump 30which conveys fuel from the reservoir 8 to the flushing tank 12 in thesame manner as shown in FIG. 2. In both arrangements, the discharge lineof pump 30 is controlled by a float valve 13a.

FIG. 4 represents a highly simplified modification of the arrangementshown in FIG. 1. In this case, the fuel is conveyed from the reservoir 8by means of a pump 7 and via a feed line 9 to the housing 1, and thefuel accumulating in the chamber 10 is recycled by means of a pump 33via a line 11 into the fuel reservoir 8.

In the second embodiment of the device according to the invention,represented in FIG. 5, the differential filling height is not obtainedby overflowing vessels, but rather by means of flushing tanks 35 and 36,whose floats 37 and 38 actuate the valves 39 and 40, which in turncontrol the flow of fuel into the tanks. The fuelis conveyed by means ofa pump 41, which aspirates fuel from the reservoir 8, and which conveysthe fuel through a line 42 to the valves 39 and 40. From tanks 35 and36, fuel will reach a suction tube (not shown) in the same manner as inthe first arrangement described hereinbefore, via a solenoid valvehaving chambers 21, 22 and 23.

What is claimed is:

i. In a fuel metering device for an internal combustion engine whereinthe fuel feed pressure of the device is determined by the static heightof the fuel in a vessel from which a fuel line leads to a suction tube,the improvement comprising at least two vessels of different fillinglevel, means for feeding fuel into each of said vessels, valve means forconnecting said vessels alternatingly or simultaneously with said fuelline, and control means for actuating said valve means in depeneach ofsaid vessels in order to maintain differential static heights of fuel insaid vessels and comprising means for recycling overflowing fuel.

5. The improvement as described in claim 4, wherein said means forcontrolling the static height of fuel in each of said vessels compriseoverflow means.

6. The improvement as described in claim 4, wherein said means forcontrolling the static height of fuel in each of said vessels comprisefloating valve means.

7. The improvement as described in claim 4, wherein said means forfeeding fuel into said vessels comprise pump means.

8. The improvement as described in claim 4, wherein said means forfeeding fuel intosaid vessels comprise a flushing tank.

9. The improvement as described in claim 4, wherein said means forfeeding fuel into said vessels comprise pump means, a flushing tank fedby said pump means, said valve means controlling the flow of fuel to andfrom said flushing tank.

10. The improvement as described in claim 9, wherein said valve meanscomprise float means in said flushing tank.

11. The improvement as described in claim 4, wherein said means forrecycling overflowing fuel comprise pump means.

12. The improvement as described in claim 4, wherein said means forrecycling overflowing fuel comprise a flushing tank.

13. The improvement as described in claim 4, wherein said means forrecycling overflowing fuel comprise pump means, a flushing tank fed bysaid pump means, said valve means controlling the flow of fuel to andfrom said flushing tank.

14. The improvement as described in claim 13, wherein said valve meanscomprise float valve means in said flushing tank. 1

15. The improvement as described in claim 14, wherein said float valvemeans are disposed for control ling the flow of fuel into said flushingtank.

1. In a fuel metering device for an internal combustion engine whereinthe fuel feed pressure of the device is determined by the static heightof the fuel in a vessel from which a fuel line leads to a suction tube,the improvement comprising at least two vessels of different fillinglevel, means for feeding fuel into each of said vessels, valve means forconnecting said vessels alternatingly or simultaneously with said fuelline, and control means for actuating said valve means in dependence oncharacteristic data of said engine.
 2. The improvement as described inclaim 1, wherein said control means comprises an electricallyenergizable member.
 3. The improvement as described in claim 2, whereinsaid control means is adapted for cyclic actuation of said valve means.4. The improvement as described in claim 1, comprising means forcontrolling the static height of fuel in each of said vessels in orderto maintain differential static heights of fuel in said vessels andcomprising means for recycling overflowing fuel.
 5. The improvement asdescribed in claim 4, wherein said means for controlling the staticheight of fuel in each of said vessels comprise overflow means.
 6. Theimprovement as described in claim 4, wherein said means for controllingthe static height of fuel in each of said vessels comprise floatingvalve means.
 7. The improvement as described in claim 4, wherein saidmeans for feeding fuel into said vessels comprise pump means.
 8. Theimprovement as described in claim 4, wherein said means for feeding fuelinto said vessels comprise a flushing tank.
 9. The improvement asdescribed in claim 4, wherein said means for feeding fuel into saidvessels comprise pump means, a flushing tank fed by said pump means,said valve means controlling the flow of fuel to and from said flushingtank.
 10. The improvement as described in claim 9, wherein said valvemeans comprise float means in said flushing tank.
 11. The improvement asdescribed in claim 4, wherein said means for recycling overflowing fuelcomprise pump means.
 12. The improvement as described in claim 4,wherein said means for recycling overflowing fuel comprise a flushingtank.
 13. The improvement as described in claim 4, wherein said meansfor recycling overflowing fuel comprise pump means, a flushing tank fedby said pump means, said valve means controlling the flow of fuel to andfrom said flushing tank.
 14. The improvement as described in claim 13,wherein said valve means comprise float valve means in said flushingtank.
 15. The improvement as described in claim 14, wherein said floatvalve means are disposed for controlling the flow of fuel into saidflushing tank.